Near-field Response in Lossy Media with Exponential Conductivity Inhomogeneity

Abstract

This paper examines the near-field response to source currents in lossy media with exponential conductivity inhomogeneity. The motivation for this work is to understand the modification of the polar ionosphere D region (50–90 km altitude) by powerful high frequency transmitters. The transmitted waves heat the D region plasma, causing a localized conductivity perturbation. In the presence of the DC electric field of the polar electrojet, the conductivity perturbation produces a current perturbation referred to as "antenna current" that can drive extremely/very low frequency radiation. Here we seek to understand the production of antenna current in a strongly inhomogeneous plasma. In the lower D region, the static approximation is valid, and we solve using a scalar potential description. In the upper D region, we use the magnetoquasistatic approximation and solve using a vector potential approach.